Nor was there any link with analogue or digital phones or whether or not a hands-free kit was used.

On balance, the evidence suggests there is no substantial risk of acoustic neuroma in the first decade of use - but the possibility of some effect after longer periods remains open, the researchers concluded.

Senior investigator Professor Anthony Swedlow said: "Whether there are longer-term risks remains unknown, reflecting the fact that this is a relatively recent technology."

Dr Michael Clark from the Health Protection Agency said: "This is good news but we still need to be a bit cautious."

Dr Julie Sharp, senior science information officer at Cancer Research UK, said: "This study provides further evidence that using mobile phones does not increase the risk of brain tumours.

"However, it is important that researchers continue to monitor phone users over the coming years as mobiles are still a relatively new invention."

The research is part of a bigger study that will be published next year.

A Swedish study identified an increased risk of acoustic neuromas among people who had used mobile phones for 10 years or more.

People have been concerned that the radiofrequency from phones might cause cancers, despite the absence of a known biological mechanism for this.